Method to manufacture polymer composite materials with nano-fillers for use in addtive manufacturing to improve material properties

ABSTRACT

Methods for producing 3D printing composite polymer materials for use in additive manufacturing processes are provided. The methods result in enhancing the material properties of the printing material by providing a uniform and smooth surface finish of the printing material and the nozzle extrudate for additive manufacturing processes, such as Fused Filament Fabrication. The method includes implementing impregnation techniques for combining carbon nanotubes or other nano-fillers, a polymer resin and a fiber material to produce a polymer material that can be processed into a printing material. Further, the method may include combining the carbon nanotubes or other nano-fillers and the polymer resin to form a masterbatch that may be further combined with the fiber material through an extrusion process. The method results in a printing material with enhanced material properties and smooth surface finish for the printing material and resulting nozzle extrudate for Fused Filament Fabrication.

FIELD OF THE INVENTION

The present invention generally relates to methods of manufacturingpolymer materials to be used in additive manufacturing processes formaking 3D objects. More particularly, the present invention relates tomethods of combining carbon nanotubes or other nano-fillers with fiberfilled polymers to produce printing material with superior mechanical,electrical, and thermal properties for additive manufacturing.

BACKGROUND

Rapid prototyping, additive manufacturing, or 3D printing processesutilize a three-dimensional (3D) CAD file to produce a 3D object.Numerous methodologies have been described in prior art, the most commonincluding selective-laser-sintering (“SLS”), stereolithography (“SLA”),inkjet printing, and extrusion based 3D printing or FFF (fused filamentfabrication).

Several types of low temperature thermoplastic polymers, such as ABS(acrylonitrile butadiene styrene) and PLA (polylactic acid) are used inadditive manufacturing for prototyping. Higher-end engineering polymers,such as polyetheretherketone (PEEK), polyetherketoneketone (PEKK),polyphenylsulphone (PPSU), polycarbonate (PC), and polyetherimide (PEI)are used for fixtures or higher temperature applications. Fiber fillers,such as carbon, or glass fibers, have been added to polymers used foradditive manufacturing to enhance the mechanical properties. Althoughthe stiffness increases with increased fiber loading as expected, thetensile strength does not increase proportionally with the fiber loadingfor 3D printed parts. Testing of these 3D printed parts havedemonstrated that the tensile strength for these parts are around 40% to60% less than the tensile strength of the same parts made throughinjection molding or machining

Using a specific example involving Fused Filament Fabrication, carbonfiber and glass fiber polymer filaments have a rough, uneven surface. Asthe fiber loading increases, the surface roughness and unevenness infilament diameter also increases. The surface roughness and aberrationsresult in a brittle filament, which is difficult to handle and processin a 3D printer. Moreover, filament with surface variations can causethe motor and incoming filament to stall, resulting in voids or gaps inthe printed part/objects. The nozzle extrudate, material exiting theprinting nozzle, also shares the same surface roughness and brittlenature of the feed filament. The extrudate boundaries created during theprinting of a 3D object are the mechanically weak areas of the part.Thus, under loading, the 3D printed parts fail at these boundariesthrough crack propagation, delamination, or another failure mode. Forachieving the best possible material properties for Fused FilamentFabrication, the polymer filament and resulting nozzle extrudate musthave a uniform and smooth surface.

Therefore, there exists a need to improve the material properties offiber filled polymer materials used for additive manufacturing.

Furthermore, there exists a need to achieve a smoother and uniformsurface finish for the printing material (and nozzle extrudate for FusedFilament Fabrication) to enhance the material properties and improve theease of handling.

SUMMARY OF THE INVENTION

An aspect of the present invention provides a method for producing aprinting material, for use in additive manufacturing processes, in orderto enhance the properties of the printing material and nozzle extrudatefor Fused Filament Fabrication, the method comprising: combining carbonnanotubes or other nano-fillers into a neat polymer resin to form amasterbatch, using inclusion techniques; combining a fiber-filledpolymer material with the masterbatch in order to produce the printingmaterial, implementing the compounding, melt mixing, spinning (dry, wetand jet), solution processing, and/or in-situ polymerization,techniques; where the fiber-filled polymer material is combined in themasterbatch during an extrusion process extruding a printing material.The combined material may then be processed to produce feed material fora specific 3D printing method (e.g. powder for Selective LaserSintering, filament for Fused Filament Fabrication, etc.), such that themethod results in a uniform and smooth surface finish of the printingmaterial that helps in enhancing the material properties of the printingmaterial and nozzle extrudate for Fused Filament Fabrication.

Another aspect of the present invention provides a method for producinga printing material, for use in additive manufacturing processes, inorder to enhance the properties of the printing material and nozzleextrudate for Fused Filament Fabrication, the method comprising:combining carbon nanotubes or other nano-fillers with a fiber materialtogether into a polymer resin to form a printing material, usingcompounding, melt mixing, spinning (dry, wet and jet), solutionprocessing, and/or in-situ polymerization techniques, and allowing foruniform and even distribution of the carbon nanotubes or othernano-fillers and the fiber material within the polymer resin. Thecombined material may then be processed to produce feed material for aspecific 3D printing method (e.g. powder for Selective Laser Sintering,filament for Fused Filament Fabrication, etc.), such that the methodresults in a uniform and smooth surface finish of the printing materialthat helps in enhancing the properties of the printing material andnozzle extrudate for Fused Filament Fabrication.

Yet another aspect of the present invention provides a method forproducing a printing material, for use in additive manufacturingprocesses, in order to enhance the properties of the printing materialand nozzle extrudate for Fused Filament Fabrication, the methodcomprising: coating, grafting, or growing carbon nanotubes or othernano-fillers evenly on surface of a fiber material; combining of themodified fiber material within a polymer resin. The processed materialmay then be processed to produce feed material for a specific 3Dprinting method (e.g. powder for Selective Laser Sintering, filament forFused Filament Fabrication, etc.), such that the method results in auniform and smooth surface finish of the printing material that helps inenhancing the material properties of the printing material and nozzleextrudate for Fused Filament Fabrication.

An aspect of the present invention involves the extrusion process beingperformed using a twin extruder with a high ratio screw to provide ahigh level of shear and maximize dispersion of the carbon nanotubes orother nano-fillers and fiber material in polymer. Other dispersiontechniques may involve higher screw speed, low material throughputs, andthe positioning of the filler feeding.

Another aspect of the present invention involves the combining of thecarbon nanotubes or other nano-fillers and the fiber-filled polymermaterial to maximize the wettability and dispersion of the nano-fillerand the fiber material in the printing material.

In aspects, other nano-fillers include but are not limited to graphenenanoplatelets, graphite powder, PTFE powder, and the like nano-fillers.Any combination or multiple combinations of these nano-fillers may alsobe combined with the fiber-filled polymer material to form the printingmaterial.

Another aspect of the present invention provides the carbon nanotubes orother nano-fillers incorporation techniques may include but are notlimited to compounding, melt mixing, spinning (dry, wet and jet),solution processing, in-situ polymerization, and the like.

A further embodiment of the present invention provides the fiber filledpolymer material may have carbon fibers, glass fibers, aramid fibers,and the like as fillers. The fiber material may be in the form ofmilled, chopped, long discontinuous, and/or continuous fibers.

An aspect of the present invention is to enhance material properties ofthe printing material by achieving smoother and uniform surface of theprinting material used in additive manufacturing processes.

Another aspect of the present invention is to enhance materialproperties of nozzle extrudate for Fused Filament Fabrication byachieving smoother and uniform surface of the extrudate used toconstruct 3D objects through additive manufacturing processes.

Another aspect of the present invention is to use nano-particle fiberswith fiber filled polymer in order to produce printing material.

A further aspect of the present invention is to use carbon nano-tubes orother nano-fillers combined with fiber filled polymer material in thepresence of a neat polymer resin for producing printing material to beused for additive manufacturing processes.

Another aspect of the present invention is to use graphenenano-platelets or other nano-filler combined with fiber filled polymermaterial in the presence of a neat polymer resin for producing printingmaterial to be used for additive manufacturing processes.

An aspect of the present invention is combining carbon nano-tubes orother nano-fillers with a neat polymer resin, and then with fiber filledpolymer in a subsequent process. For Fused Filament Fabrication, anembodiment could involve extruding into printing material directly orcompounding first and then extruding subsequently.

Yet another aspect of the present invention is to coat, graft, or grownano-fillers onto the fibers and then combine the modified fibers withneat polymer resin. This batch is then processed to create printingmaterial.

Yet another aspect of the present invention is to graft the polymerfibers with carbon nanotubes or other nano-fillers and then combine thegrafted fibers with neat polymer resin. This batch is then processed tocreate printing material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a flowchart showing a method, such as a method 100, forproducing a printing material for use in additive manufacturingprocesses, in accordance with an embodiment of the present invention.

FIG. 2 shows a flowchart depicting a method 200 for producing a printingmaterial for use in additive manufacturing processes, in accordance withan embodiment of the present invention.

FIG. 3 shows a flowchart depicting a method 300 for producing a printingmaterial for use in additive manufacturing processes, in accordance withan embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following detailed description of embodiments of the invention,numerous specific details are set forth in order to provide a thoroughunderstanding of the embodiments of the invention. However, it will beobvious to a person skilled in art that the embodiments of the inventionmay be practiced with or without these specific details. In otherinstances well known methods, procedures and components have not beendescribed in details so as not to unnecessarily obscure aspects of theembodiments of the invention.

Furthermore, it will be clear that the invention is not limited to theseembodiments only. Numerous modifications, changes, variations,substitutions and equivalents will be apparent to those skilled in theart, without parting from the spirit and scope of the invention.

The present invention relates to a method of producing a printingmaterial, to be used in additive manufacturing processes, by usingnano-sized particles, such as carbon nano-tubes. The present inventionfurther aims to result in enhancing the material properties of theprinting material and nozzle extrudate for additive manufacturingprocesses, such as Fused Filament Fabrication. For achieving the highestpossible material properties in the printing materials and nozzleextrudate for Fused Filament Fabrication, smooth and uniform surface ofthe printing material plays a crucial role. Therefore, the presentinvention relates to use of nano sized particles, such as carbonnanotubes, with fiber filled polymer, in order to achieve smooth anduniform surface and in-turn enhance the material properties of theprinting material and nozzle extrudate for Fused Filament Fabrication,and thereby enhancing the material properties of 3D printed objects.

For 3D printing or additive manufacturing processes, the wettability andsurface finish of fibers are of particular importance due to manysurface interfaces present in a 3D printed object. Rough contactingsurfaces result in defects, voids, or asperities. These asymmetricalfeatures act as stress concentrators in the part under load, causingpremature failure. In order to maximize the surface adhesion betweenindividual extrudate sections and layers, carbon nanotubes or othernano-fillers are added to fiber filled printing materials. To maximizethe dispersion and wettability of carbon nanotubes or other nano-fillersand fiber material in 3D printing material, the present inventionprovides efficient methods of combining carbon nanotubes or othernano-fillers with fiber filled polymer material.

FIG. 1 depicts a flowchart showing a method for producing a printingmaterial for use in an additive manufacturing process, in accordancewith an embodiment of the present invention. The technology used in thepresent invention for producing 3D printing material includes and is notlimited to extrusion processes. Combining carbon nanotubes or othernano-fillers with resin involves compounding, melt mixing, spinning(dry, wet and jet), solution processing, and in-situ polymerization.This process changes the physical, thermal, electrical or aestheticcharacteristics of the plastic. The final product is called a compoundor composite.

FIG. 1 shows a flowchart depicting a method 100 for producing a 3Dprinting polymer material with enhanced material properties. Asmentioned in the background, carbon fiber and glass fiber printingmaterials have a rough, uneven surface that further results in brittlematerial, which is difficult to handle and process in a 3D printer.Therefore, enhanced material properties of the printing material are arequirement in 3D printing. Hence, embodiments of the present inventionprovide for use of carbon nanotubes or other nano-fillers with thefiber-filled polymers that results in a smooth surface finish andconsequently, in enhanced material properties. According to FIG. 1, atsteps 102-104, carbon nanotubes (CNT) or other nano-fillers may becombined with a neat (unfilled) polymer resin to form a masterbatch. Asmentioned above, combining processes may include compounding, meltmixing, spinning (dry, wet and jet), solution processing, in-situpolymerization, and like processes. At step 104, a pelletizedmasterbatch of carbon nanotubes or other nano-fillers in polymer resinis formed.

After the masterbatch has been created, the masterbatch may be furthercombined with a fiber filled polymer material, at step 106.Consequently, a 3D printing polymer material is produced using carbonnanotubes or other nano-fillers, at step 108. In an embodiment of thepresent invention, the masterbatch may be first combined with the fiberfilled polymer material to form a printing material that may be furtherprocessed into polymer material. In a specific embodiment, themasterbatch may be combined with the fiber filled polymer materialduring an extrusion process, resultantly drawing out polymer filamentfor Fused Filament Fabrication (referred to as “FFF”) simultaneously.

The method 100 results in a uniform and smooth surface finish of the 3Dprinting material that helps in enhancing the material properties of theprinting material.

FIG. 2 shows a flowchart depicting a method 200 for producing a printingmaterial for use in an additive manufacturing process, in accordancewith an embodiment of the present invention. According to FIG. 2, thecarbon nanotubes or other nano-fillers may be combined with a fibertogether within a polymer resin, at step 202. Thereafter, at step 204, apelletized master batch of carbon nanotubes or other nano-fillers andfiber in the polymer resin is formed. Consequently, a 3D printingpolymer material for additive manufacturing processes, such as fusedfilament fabrication, may be obtained, at step 206. The method 200allows for uniform and even distribution of carbon nanotubes or othernano-fillers and fiber within the polymer matrix. In an embodiment, thecombined printing material may be combined in a twin extruder drawingout a polymer filament for use in 3D printing processes.

FIG. 3 shows a flowchart depicting a method 300 for producing a printingmaterial for use in additive manufacturing process, in accordance withan embodiment of the present invention. According to FIG. 3, at step302, carbon nanotubes or other nano-fillers may be directly appliedthrough grafting or growing on the fiber surface or coated evenly on thefiber surface prior to combining with a polymer resin. Thereafter, atstep 304, the modified fiber material may be combined with a polymerresin, thereby producing a 3D printing material. Consequently, at step306, the 3D printing material may be processed to form a 3D printingmaterial further to be used in additive manufacturing processes.

In an embodiment of the present invention for an extrusion process, themasterbatch may be combined with the fiber filled polymer material in anextruder, such as a twin extruder, and preferably under the highestshear possible to maximize dispersion.

In an embodiment of the present invention, a mixture of carbon nanotubesand graphene nanoplatelets may also be combined with the fiber materialand the polymer resin to form the 3D printing material. This may help inoptimizing the mechanical strength, thermal conductivity, electricalconductivity, and ease of handling for 3D printing material.

In an embodiment of the present invention, the fiber filled polymermaterial may be used in the form of pellets for extrusion, to form theprinting material.

In an embodiment, the polymer resin may have carbon fibers, glassfibers, aramid fibers, and the like to form fiber filled polymer. Thefiber material may be in the form of milled, chopped, longdiscontinuous, and/or continuous fibers.

In another embodiment of the present invention, the polymer resin may bea thermosetting polymer resin, or may be a polyaryletherketone (PAEK),polyethertherketone (PEEK), polyetherketoneketone (PEKK), polyethylene(PE), polyetherimide (PEI commonly known as Ultem), polyethersulfone(PES), polysulfone (PSU commonly known as Udel), polyphenylsulfone (PPSUcommonly known as Radel), polyphenylene oxides (PPOs), acrylonitrilebutadiene styrene (ABS), polylactic acid (PLA), polyglycolic acid (PGA),polyamide-imide (PAI commonly known as Torlon), polystyrene (PS),polyamide (PA), polybutylene terephthalate (PBT), poly(p-phenylenesulfide) (PPS), polyethersulfone (PESU), polyphenylene ether (commonlyknown as PrimoSpire), and polycarbonate (PC) and the like.

In another embodiment of the present invention, the polymer resins maybe combined together to improve the printability and fiber/nano-fillerwettability. One such example is a blend of polyethertherketone (PEEK)with polyphenylsulfone (PPSU) with a composition in the range of 60:40to 90:10 respectively.

In an embodiment of the present invention, the amount of fiber or carbonnanotube or other nano-filler material in the polymer resins may rangefrom 5% up to 60%. The following examples of compositions ofpolyetherimide (PEI) and polyethertherketone (PEEK) resins: 30% CNTloading, 15% CNT and 15% CF, 10% CNT and 10% CF (Carbon Fiber). A blendof 15% CNT and 15% graphene may also be combined in the abovethermoplastic resins. In a preferred embodiment one may change theloading of CNT and graphene from as low as 1% CNT or graphene up to ashigh as 40% graphene or CNT.

Advantageously, embodiments of the present invention provide a method toproduce a 3D printing material by using carbon nanotubes or othernano-fillers. Carbon nanotubes have been shown to provide a smoother,more uniform material surface through the present invention. Thissmooth, uniform surface has provided decreased nozzle pressure duringprinting, improved ease of handling, potentially better materialproperties, and potentially improved z-layer adhesion (due to the highersurface area contact from smoother extrudate surfaces). Furthermore,with its three dimensional structure, carbon nanotubes may be morelikely to be aligned through the printing process as compared toGraphene nanoplatelets or other nano-fillers.

Further, a smooth uniform extrudate surface for Fused FilamentFabrication is achieved which enables achievement of high possiblematerial properties. Also, the surface roughness and diameterfluctuations are reduced when adding carbon nanotubes with carbon fiberas compared to only carbon fiber.

Further advantages of the embodiments of the present invention aremethods herein including a polymer material including a blend of carbonnanotubes or other nano-fillers and fibers which provide a smoother,more uniform surface, a more flexible, easier to handle printingmaterial compared to a fiber-filled printing material. Also, smootherand more uniform extrudate for Fused Filament Fabrication may bedeveloped as compared to a fiber-filled extrudate. Enhanced materialproperties compared to fiber-filled parts may also be yielded fromembodiments of the present invention.

Embodiments of the present invention are suitable for additivemanufacturing processes, such as fused filament fabrication (FusedFilament Fabrication), selective laser sintering (Selective LaserSintering), droplet based, jetting methods and the like.

We claim: 1) A method for producing a printing material, for use inadditive manufacturing processes, in order to enhance the properties ofthe printing material and nozzle extrudate, the method comprising:combining a nano-filler, such as carbon nanotubes, into a neat polymerresin to form a masterbatch, using combining techniques; combining afiber-filled polymer material with the masterbatch in order to producethe printing material, implementing the combining techniques; where thefiber-filled polymer material is combined with the masterbatch during anextrusion process extruding a printing material; and such that themethod results in a uniform and smooth surface finish of the printingmaterial that helps in enhancing the material properties of the printingmaterial. 2) The method as claimed in claim 1, wherein the extrusionprocess is performed using a twin extruder under highest shear possibleto maximize dispersion of the nano-fillers and fiber material inpolymer. 3) The method as claimed in claim 1, wherein the nano-fillersinclude but are not limited to carbon nanotubes, graphene nanoplatelets,graphite powder, PTFE powder, a combination or multiple combinations ofthese nano fillers and the like. 4) The method as claimed in claim 1,wherein the fiber filled polymer material may be used in the form ofpellets for extrusion. 5) The method as claimed in claim 1, wherein thecombining techniques may include and not limited to compounding, meltmixing, spinning (dry, wet and jet), solution processing, and in-situpolymerization, 6) The method as claimed in claim 1, wherein the fiberfilled polymer material may have carbon fibers, glass fibers, aramidfibers, or a mixture of carbon, aramid, and glass fibers, and the likeas fillers that may be in the form of milled, chopped, longdiscontinuous, and/or continuous fibers. 7) The method as claimed inclaim 1, wherein the polymer resin may be a thermosetting polymer resin,or may be one from the group consisting of polyaryletherketone (PAEK),polyethertherketone (PEEK), polyetherketoneketone (PEKK), polyethylene(PE), polyetherimide (PEI commonly known as Ultem), polyethersulfone(PES), polysulfone (PSU commonly known as Udel), polyphenylsulfone (PPSUcommonly known as Radel), polyphenylene oxides (PPOs), acrylonitrilebutadiene styrene (ABS), polylactic acid (PLA), polyglycolic acid (PGA),polyamide-imide (PAI commonly known as Torlon), polystyrene (PS),polyamide (PA), polybutylene terephthalate (PBT), poly(p-phenylenesulfide) (PPS), polyethersulfone (PESU), polyphenylene ether (commonlyknown as PrimoSpire), and polycarbonate (PC) and the like. 8) A methodfor producing a printing material, for use in additive manufacturingprocesses, in order to enhance the properties of the printing materialand nozzle extrudate, the method comprising: combining a nano-filler,such as carbon nanotubes, with a fiber material together into a polymerresin to form a printing material, using combining techniques, andallowing for uniform and even distribution of the nano-filler and thefiber material within the polymer resin; such that the method results ina uniform and smooth surface finish of the printing material that helpsin enhancing the properties of the printing material and nozzleextrudate. 9) The method as claimed in claim 8 further comprisesformation of combined, pelletized printing material; and extrusion ofthe printing material from the pelletized material to produce theprinting material, using an extruder, such as a twin extruder. 10) Themethod as claimed in claim 8, wherein the combining of the nano-fillers,the fiber material and the polymer resin maximizes the wettability anddispersion of the nano-fillers and the fiber material in the printingmaterial. 11) The method as claimed in claim 8, wherein the nano-fillersinclude but are not limited to carbon nanotubes, graphene nanoplatelets,graphite powder, PTFE powder, a combination or multiple combinations ofthese nano fillers, and the like. 12) The method as claimed in claim 8,wherein the combining techniques may include and not limited tocompounding, melt mixing, spinning (dry, wet and jet), solutionprocessing, and in-situ polymerization, 13) The method as claimed inclaim 8, wherein the fiber material may be carbon fibers, aramid fibers,or glass fibers or a mixture of carbon, aramid, and glass fibers, andthe like that may be in the form of milled, chopped, long discontinuous,and/or continuous fibers. 14) The method as claimed in claim 8, whereinthe polymer resin may be a thermosetting polymer resin, or may be onefrom the group consisting of polyaryletherketone (PAEK),polyethertherketone (PEEK), polyetherketoneketone (PEKK), polyethylene(PE), polyetherimide (PEI commonly known as Ultem), polyethersulfone(PES), polysulfone (PSU commonly known as Udel), polyphenylsulfone (PPSUcommonly known as Radel), polyphenylene oxides (PPOs), acrylonitrilebutadiene styrene (ABS), polylactic acid (PLA), polyglycolic acid (PGA),polyamide-imide (PAI commonly known as Torlon), polystyrene (PS),polyamide (PA), polybutylene terephthalate (PBT), poly(p-phenylenesulfide) (PPS), polyethersulfone (PESU), polyphenylene ether (commonlyknown as PrimoSpire), and polycarbonate (PC) and the like. 15) A methodfor producing a printing material, for use in additive manufacturingprocesses, in order to enhance the properties of the printing materialand nozzle extrudate, the method comprising: coating, grafting, and/orgrowing a nano-filler evenly on surface of a fiber material, modifyingthe fiber material; combining of the modified fiber material within apolymer resin to form the printing material, implementing combiningtechniques; and such that the method results in a uniform and smoothsurface finish of the printing material that helps in enhancing thematerial properties of the printing material. 16) The method as claimedin claim 15, wherein the combining of the nano-filler, the fibermaterial and the polymer resin maximizes the wettability and dispersionof the nano-filler and the fiber material in the printing material. 17)The method as claimed in claim 15, wherein the nano-filler include butare not limited to carbon nanotubes, graphene nanoplatelets, graphitepowder, PTFE powder, a combination or multiple combinations of thesenano fillers, and the like. 18) The method as claimed in claim 15,wherein the combining techniques may include and not limited tocompounding, melt mixing, spinning (dry, wet and jet), and solutionprocessing, in-situ polymerization. 19) The method as claimed in claim15, wherein the fiber material may be carbon fibers, aramid fibers, orglass fibers or a mixture of carbon, aramid and glass fibers and thelike that may be in the form of milled, chopped, long discontinuous,and/or continuous fibers. 20) The method as claimed in claim 15, whereinthe polymer resin may be a thermosetting polymer resin, or may be onefrom the group consisting of polyaryletherketone (PAEK),polyethertherketone (PEEK), polyetherketoneketone (PEKK), polyethylene(PE), polyetherimide (PEI commonly known as Ultem), polyethersulfone(PES), polysulfone (PSU commonly known as Udel), polyphenylsulfone (PPSUcommonly known as Radel), polyphenylene oxides (PPOs), acrylonitrilebutadiene styrene (ABS), polylactic acid (PLA), polyglycolic acid (PGA),polyamide-imide (PAI commonly known as Torlon), polystyrene (PS),polyamide (PA), polybutylene terephthalate (PBT), poly(p-phenylenesulfide) (PPS), polyethersulfone (PESU), polyphenylene ether (commonlyknown as PrimoSpire), and polycarbonate (PC) and the like.